Welding method



g- 1938- H. s. MEHLHOUSE 2,127,648

WELDING METHOD Filed Sept. 26, 1936 /}V VIP/V701? H G. MEHL/IOUSE Patented Aug. 23, 1938 UNITED STATES,

WELDING METHOD Harvey G. Mehlhouse, Naperville, Ill., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application September 26, 1936, Serial No. 102,689

4 Claims.

This invention relates to welding methods, and more particularly to methods for welding contacts on switch members.

In the manufacture of certain types of electrical apparatus it is desirable to use gold, silver, platinum or other costly metals for the contacting portions of switch elements. In order to restrict the quantity of expensive contactmetal required,

it is usually applied on the switch elements in the form of small individual contacts preformed to the required size and shape. Thecontacts may be attached by riveting, but welding is more economical and satisfactory. Because" the contacts are small and fragile they are diflicult to handle II and weld. Special equipment has been employed for this purpose and careful control of the operation is necessary to insure satisfactory results.

An object of this invention is to provide improved methods for welding materials securely and economically.

In one embodiment of the invention contact material, in the form of a continuous strip, is welded across the aligned ends of a plurality of internested switch members and subsequently severed at the junctions between the members to provide individual contacts on the members.

A complete understanding of the invention may be had from the following detailed description taken in conjunction with the appended drawing,

so in which Fig. 1 is a perspective view showing apparatus for welding contact metal on switch members in accordance with one form of the invention;

Fig. 2 is a perspective view of a completed switch member;

Fig. 3 is a vertical section of a portion of the apparatus shown in Fig. 1, and

Fig. 4 is a plan view showing a method for applying contact metal on a plurality of springs,

embodying an alternative form of the invention.

Contacts are used extensively on switch members of various types employed to control electrical circuits in communication apparatus. These switch members or springs are usually made of brass, nickel-silver, bronze or other relatively cheap materials and the contacts are formed of noble metals or their alloys. One type of switch element or spring l0 (Fig. 2) to which the invention is particularly adapted has a body portion I l 5 and a series of uniformly spaced projections l2 along one edge thereof.. In service these projections are engaged by other members and it is, therefore, desirable to apply contacts l3 to the engaged surface of the projecting portions. The

5 most economical and serviceable form of contact projections on the switch members.

,for this type of spring is an elongated bar located along the middle of the projection with its axis parallel to the axis of the switch member.

In one embodiment of the invention the contact metal is welded to the member in the form of a continuous strip or strand it having a cross-sectional contour most suitable for welding and service performance. The contact strip may be bimetallic, for example, having a base of nickelsilver and facing of noble metal, or may be com-= posed entirely of noble metal. The strip is formed or rolled to shape previous to the welding operation.

The welding operation can be performed on a machine of conventional construction as shown in Fig. l. The switch members are fed between two cylindrical welding electrodes or rolls in pairs with their projecting portions internested and the members in the same plane. As the projections are uniformly spaced, they can be nested readily and are aligned with their middle portions coinciding.

' In the welding apparatus, the lower electrode l5 which has the form of a roller, is mounted on a shaft l6 and has a peripheral Shoulder I! at each end for positioning the parts in proper relationship. The upper electrode I8, also a roller, is aligned vertically with the lower electrode and is mounted above and in contact with the nested parts on a shaft I 9. The two electrode shafts are connected to a suitable power source (not shown) for rotating the rolls and conveying the switch members between them. The portion of the upper electrode surface in contact with the switch members is covered with rubber 20, fibre or other insulating material. In the surface of the upper electrode is an uninsulated peripheral groove 2| formed to the cross-section of the contact metal strip and aligned with the middle portion of the The contact metal strip is fed to this groove from a supply roll (not shown) and. welded to the switch members as they progress between the electrodes by the passage of welding current of suitable characteristics between the electrodes. Well known means can be used for driving the electrodes and for supplying and controlling the welding current which passes fromthe groove through the contact metal strip and lower electrode to weld the strip efliciently and securely to the nested members. For an installation in which the switch members are advanced between therolls at a speed of ten feet per minute, sixty cycle current having a voltage adapted to the size and composition of the switch members and contact metal strip is satisfactory.

Subsequent to the welding the parts are sep arated in a cutting or punching die of conventional construction. In this operation the contact metal is severed at the edges of each proiection on the switch member, leaving the contact on the projection. Scrap metal produced in this operation is readily recast and reformed into strip for reuse.

In another type of electrical equipment contacts are applied to bifurcated ends of individual springs. As shown in Fig. 4 springs 25 of this type can be fed to the welding electrodes with their bifurcated ends 26 internested to apply the contact metal tape or strand 2'! across a plurality of the springs in the above described welding apparatus. After the welding operation the contact metal is severed at the junctures between the individual springs to complete the process.

Certain types oi switch members do not internest easily. In the manufacture of these parts the contact metal strand preferably is welded to a metal strip or blank which is subsequently punched into switch members of the required shape. The welding and blanking operations are both located from one reference edge of the blank so that the contacts will be properly positioned on the completed part. The contact metal adhering to scrap produced in the blanking is recovered by dissolving the base or blank material in a suitable acid.

Other modifications and variations of the above described methods and processes can be adapted to the manufacture of members of various types to which contacts are applied and it is to be understood that the invention is limited only by the scope of the appended claims.

What is claimed is:

1. A method for attaching contacts on switch springs having bifurcated ends, comprising placing a pair of springs in end to end relationship with the bifurcations internested, welding a continuous strip of contact metal on the bifurcated ends transverse to the axis of the springs, and severing the contact metal at the juncture between the springs.

2. A method for securing contacts to switch members having a plurality oi projections along one side, comprising placing two of the members together with their projecting portions interlocked in one plane, welding a continuous strip of contact material on the surface of the members across the interlocked projections, and cutting the contact metal at the juncture between the members.

3. A method of making contact springs for use in electrical apparatus comprising the steps of forming sheet material into members each having a body for mounting the member in the apparatus and a portion extending therefrom for engaging other members, forming contact metal into tape. associating a plurality of the formed members into predetermined relative positions with their extending portions aligned, welding the tape continuously to the aligned portions of the members, and severing the tape at the juncture between the members to form a bar of contact metal on the engaging portion of each memher.

4. A method of making electrical contact members, each having a bifurcated portion, comprising forming the members from sheet material, associating a number of the members with their bifurcations internested, forming contact metal into strip form, welding the contact metal strip to the associated members, and severing the con tact metal at the juncture between the members.

HARVEY G. MEHLI-IOUSE. 

